Background. Survival among dialysis patients has always been the focus of ESRD care because of the high mortality rate. However, the mortality of ESRD patients has not improved over the past 15 years in spite of improvements in technology that one would expect to improve patient survival. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the death rate of 24% annually among the ESRD population in the U.S. remains "unacceptably high". With the steady increase in the incidence and prevalence of patients with ESRD, it is becoming an even more urgent public health problem both medically and economically. Objective. The vast majority of ESRD patients (more than 90%) receive hemodialysis three times per week from the nation's roughly 4,000 Medicare-certified dialysis facilities. Substantial differences in patient mortality rate might be influenced by patient case mix factors as well as dialysis facility characteristics. Facilities policies governing dialysis care and associated practice patterns, as opposed to patient-specific causes, have been under-researched and might play an important role in influencing patient outcomes. During the past fifteen years, the tremendous growth and consolidation of large dialysis chains have raised concerns about the quality of care delivered to ESRD patients in many areas. Accordingly, this application seeks to 1) examine whether patients treated in dialysis chain facilities have better or worse survival after adjusting for other facility characteristics and a wide range of patient characteristics such as demographics, clinical characteristics, and comorbidities;2) evaluate and compare the effect of facility ownership (for-profit status) versus chain status on patient mortality;and 3) examine whether the relationship between dialysis chain status and patient mortality might be mediated through providers'economically driven practices. Methods. The research will rely on two primary sources of data: 1) standard analytical files (SAFs) collected and maintained by the United States Renal Data System (USRDS) as of December 2005, which is the most recent available data for researchers (as of March 2008);and 2) CMS "Dialysis Compare" data. Additional sources of data include CMS Renal Cost Report data and the 2000 US Census data to ascertain ZIP code-level socioeconomic characteristics. These national databases provide the most comprehensive information on the characteristics of dialysis units in the United States. Multilevel regression models will be used to estimate the impact of dialysis chain status on mortality among patients who initiated outpatient hemodialysis in 2002. Significance. To date, little is known regarding whether there are differences in patient outcomes between patients receiving dialysis care from facilities affiliated with chains versus nonchain facilities. The potential findings of the proposed study will shed new light on the relationship between type of facility and patient mortality, aid clinicians and policy makers in identifying optimal management practices, and eventually improve care and outcomes of ESRD patients. PUBLIC HEALTH RELEVANCE: According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the death rate of 24% annually among the end-stage renal disease (ESRD) population in the U.S. remains "unacceptably high." With the steady increase in the incidence and prevalence of patients with ESRD, it is becoming an even more urgent public health problem both medically and economically. The vast majority of ESRD patients (more than 90%) receive hemodialysis 3 times per week from the nation's roughly 4,000 Medicare-certified dialysis facilities. Substantial differences in patient mortality rate might be influenced by dialysis facility characteristics in addition to patient case mix factors. Facility-specific policies governing dialysis care and associated practice patterns, as opposed to patient-specific causes, have been under-researched and might play an important role in influencing patient outcomes. In this project, the proliferation of chains providing efficient dialysis services will be examined with regard to their influence on patient outcomes and mortality. The potential findings of the proposed study will shed new light on the relationship between type of facility and patient mortality, aid clinicians and policy makers in identifying optimal management practices, and eventually improve care and outcomes of ESRD patients.